NGSI-LD library

PyNgsild is a library to communicate/integrate simply with a FIWARE Context Broker using the NGSI-LD API.

Concepts

The library defines Classes for each element of the NGSI-LD data model, namely:

• Entity,
• Property,
• Relationship.

Then, a ContextBroker Class implements the NGSI-LD operations (e.g. Create Entity). The current implementation supports:

• Create Entity,
• Update Entity Attributes,
• Append Entity Attributes,
• Delete Entity,
• Retrieve Entity,
• Query Entities

How To

Create an entity

A simple entity can be created with:

from pyngsild.entity import Entity

entity_1 = Entity(id='uri:entity_id', type='entity_type')

Then, the NGSI-LD context of this entity can be set with:

entity_1.at_context = 'https://my/context'

Create a property

A simple property could be created with:

from pyngsild.proprel import Property

property_1 = Property(name='property_name', value='property_value')

A complete property could be created with:

property_2 = Property(name='property_name', value='property_value',
                       observed_at='some_date_time', unit_code='a_unit_code',
                       datasetid='uri:prop:datatsetid')

GeoProperty are supported and can be created with:

from pyngsild.proprel import GeoProperty

geo_property = GeoProperty(name='location',
                           value='{'type': 'Point',
                                   'coordinates': [46.969047065728226, 19.649525998191066]}')

It is then easy to add a property to an entity or to another property:

property_1.add(geo_property)
entity_1.add(property_1)

Create a relationship

It really follows the same principle as Property (with obviously different type of attributes). For instance, to create relationship:

from pyngsild.proprel import Relationship

relationship_1 = Relationship(name='relationship_name', object_='to:uri:object',
                         observed_at='some_date_time',
                         datasetid='uri:rel:datasetid')

a property can be added to a relationship:

relationship_1.add(property_2)

And a relationship can be added to a property:

property_1.add(relationship_1)

At this stage, the entity_1 has a property property_1, which has a geo_property and a relationship_1, which itself has a property property_2.

The NGSI-LD json representation of this entity can be simply displayed with:

print(entity_1.to_ngsild())

Context Broker

Operations to a NGSI-LD Context Broker are supported through the ContextBroker Class. For instance, creating an entity into a Context Broker is simply done with:

from pyngsild.ctxbroker import ContextBroker

ctxb = ContextBroker()
response = ctxb.create_entity(entity=entity_1)

ContextBroker manage authorisation tokens to access a Context Broker, that is getting and renewing an access token. For this, ContextBroker() requires the following environment variables:

• PYNGSILD_SSO_SERVER_URL: Environment variable for the SSO server URL
• PYNGSILD_SSO_CLIENT_ID: Environment variable for the client_id
• PYNGSILD_SSO_CLIENT_SECRET = Environment variable for the client_secret

Also, the following environment variable is required for the URL of the Context Broker:

• PYNGSILD_CB_HOST: Environment variable for Context Broker host URL

Installation

pip install git+https://{token}@github.com/stellio-hub/pyngsild

Or alternatively:

pip install git+ssh://git@github.com/stellio-hub/pyngsild